The Key System (or Key Route) was a privately owned company that provided mass transit in the cities of Oakland, Berkeley, Alameda,[2] Emeryville, Piedmont, San Leandro, Richmond, Albany, and El Cerrito in the eastern San Francisco Bay Area from 1903 until 1960, when it was sold to a newly formed public agency, AC Transit.

The system began as a consolidation of several streetcar lines assembled in the late 1890s and early 1900s by Francis Marion "Borax" Smith and his business interests.

After consolidating local lines under one company, Smith sought to compete with the Southern Pacific commuter ferry market as well as develop new streetcar suburbs in the East Bay.

Smith purchased the railroad in order to gain access to its right of way and waterfront operations, as well as use the abandoned pier as a starting point for his own passenger mole.

[3] Transbay service began on October 26, 1903,[4] with a four-car train carrying 250 passengers, departing downtown Berkeley for the ferry to San Francisco.

[5] Before the end of 1903, Frank C. Havens, the general manager of the SFOSJR, devised the idea of using a stylized map on which the system's routes resembled an old-fashioned key, with three "handle loops" that covered the cities of Berkeley, Piedmont (initially, "Claremont" shared the Piedmont loop) and Oakland, and a "shaft" in the form of the Key pier, the "teeth" representing the ferry berths at the end of the pier.

[7] After it went bankrupt in December 1923, it was re-organized as the Key System Transit Co., adopting a marketing concept as the name of the company.

Following the Great Crash of 1929, a holding company called the Railway Equipment & Realty Co. was created, with the subsidiary Key System Ltd running the commuter trains.

[9] The same year E. Jay Quinby hand published a document exposing the ownership of National City Lines (General Motors, Firestone Tire, and Phillips Petroleum).

In it he wrote "This is an urgent warning to each and every one of you that there is a careful, deliberately planned campaign to swindle you out of your most important and valuable public utilities–your Electric Railway System".

[11] On April 9, 1947, nine corporations and seven individuals (constituting officers and directors of certain of the corporate defendants) were indicted in the Federal District Court of Southern California on two counts: 'conspiring to acquire control of a number of transit companies, forming a transportation monopoly' and 'Conspiring to monopolize sales of buses and supplies to companies owned by National City Lines'.

[13] In 1949 National City Lines, General Motors and others were convicted of conspiring to monopolize the sale of buses and related products to their subsidiary transit companies throughout the U.S.[15] Between 1946 and 1954 transbay fares increased from 20¢ to 50¢ ($3.12 to $5.67 adjusted for inflation).

Fares in this period were used to operate and for 'motorisation' which included streetcar track removal, repaving, purchase of new buses and the construction of bus maintenance facilities.

On May 6, 1933, a major fire erupted on the pier end of the mole, consuming the ferry terminal building as well as gutting the ferryboat Peralta.

The Key System's first trains were composed of standard wooden railroad passenger cars, complete with clerestory roofs.

[27] After acquisition by National City Lines, all Key vehicles including the bridge units were re-painted in that company's standard colors, yellow and green.

[28] They were generally referred to by the principal street or district they served, though the Key System did not have any formal naming scheme outside of letter designations.

The Key System's streetcars operated as a separate division under the name "Oakland Traction Company", later changed to "East Bay Street Railways.

In the early years of operation, these were supplemented by a number of smaller carbarns scattered throughout the East Bay area, many of them inherited from the pre-Key companies acquired by "Borax" Smith.

They were re-painted in the green and yellow scheme of National City Lines after NCL acquired the Key System.

"Borax" Smith and his partner Frank C. Havens first established a company called the "Realty Syndicate" which acquired large tracts of undeveloped land throughout the East Bay.